The present invention relates to a shaft, and more particularly to a pedal shaft core designed with improved structures.
As shown in FIG. 1, a conventional pedal shaft core of the prior art is constructed in such a manner that the shaft core is substantially perpendicular to the contact surface of the shaft and that it is of a ball bearing type. As a result, the pedal shaft core of the prior art is inherently defective in that it cannot be locked securely and in that it cannot be stabilized easily during the rotation thereof. In addition, the pedal shaft core of the prior art comprises the grease filling ports located at the bottom portion of the casing thereof. Thus the task of assembling a pedal shaft core of the prior art is extremely tedious, because each of the inner holes of the grease filling ports must be arranged in alignment with each of the shaft holes located in the interior of the shaft. Furthermore, the pedal shaft core of the prior art must be placed in an inclined position or in an upside down position in order to permit the user thereof to inject the grease thereinto, because all grease filling ports are located at the bottom of the shaft core.